This application claims the benefit of Japanese Patent Application No. 2012-231027 filed Oct. 18, 2012, the entire content of which is incorporated herein by reference.
The present invention relates to a two-way push-pull chain formed by connecting a plurality of link members by means of pins, and a reciprocating actuator having the two-way push-pull chain.
There is known a two-way push-pull type block chain formed by connecting a plurality of link members by means of pins as disclosed in Japanese Patent Laid-Open No. 6-286834, Japanese Patent Laid-Open No. 2011-251795, and Japanese Utility Model Laid-Open No. 3-105191. For example, as illustrated in FIGS. 7A and 7B, a block chain 700 is formed by connecting a plurality of link members 710 arranged along a longitudinal direction Y by means of pins 720. When the drive force of an unillustrated sprocket is transmitted to the block chain 700, the block chain 700 slides on a guide portion G. Accordingly, the block chain 700 moves back and forth in the longitudinal direction Y.
The conventional block chain 700 is structured to mesh with the outer peripheral surface of the sprocket while being bent around the pin 720. Thus, when the block chain 700 is pressed from both ends thereof on the guide portion G, a part of the block chain 700 may be spaced apart from the guide portion G, as illustrated in FIG. 7B, and buckled, which prevents the block chain 700 from being moved by pushing the end portion thereof to a desired position.
In other words, the conventional block chain 700 does not satisfy both the need to mesh the block chain 700 with the outer peripheral surface of the sprocket by freely bending the block chain 700 and the need to move the block chain 700 by pushing the end portion of the block chain 700 to a desired position without buckling the block chain 700. The chain disclosed in Japanese Utility Model Laid-Open No. 3-105191 is structured to be bendable in only one direction by causing a projecting piece of the link member to abut against adjacent link members. Thus, the chain cannot mesh with the outer peripheral surface of the sprocket by bending the chain freely, and the chain may be buckled in a direction opposite to the bending direction of the chain.